Transitory switch



Oct. 31, 1939. L. s. WILLIAMS 2,178,156

TRANSITORY SWITCH Filed April 21, 1938 Lawrence S. W////am.s

INVENTOR YQVL M ATTORNEYS Patented Oct. 31, 1939 UNITED STATES 'rmnsrroar swrron Lawrence S. Williams, Toledo, Ohio, assignor to Toledo Scale Manufacturing Company, Toledo, Ohio, a corporation of New Jersey Application April 21, 1938, Serial No. 203,364

' 2 Claims. (01. ZOO-33) This invention relates to transitory switches, i. e., to switches arranged to close and then open, regardless of whether or not, in any case, the switch operating handle remains in the position to which it was moved to close the switch.

The general object of the invention is to pro- F switch of this type which is not liable to be affected by dust, moisture or corrosion.

Still another object is the provision of a transitory switch constructed of an assemblage of machine formed, stamped and molded parts in whici. accurate fitting is not required.

Other objects and advantages will be apparent from the following description, in which reference is had to the accompanying drawing illustrating a preferred embodiment of my invention and wherein similar reference numerals designate similar parts throughout the several views.

In the drawing:

Figure I is a perspective view of a scale incorporating the transitory switch of my invention; Figure II is a view in perspective of the transitoryswitch per se;

Figure 111 is an enlarged plan view of the base of the transitory switch, showing the arrangement ofcontact strips;

Figure IV is an enlarged sectional view taken substantially along the line IVIV of Figure III; and

Figure V is a wiring diagram of an electrical circuit including the transitory switch of my invention.

Referring to the drawing in detail, I have illustrated my transitory switch as incorporated with a printing weighing scale comprising a base I upon which is erected a column 2 surmounted by a housing 3, a platform 4, for the reception of loads, being mounted in the usual manner on platform levers (not shown) suitably connected to load-counterbalancing mechanism (not shown). The weighing scale is equipped with an electrically-operated printing device 5, of the type illustrated and described in my United States Patent No. 2,020,982, the printing mechanism being mounted on the housing 3. To obtain a printed record, the printing device is electrically energized by a circuit which is initially closed through a transitory switch 6.

The transitory switch 6 is connected with contacts 'l of a magnetic relay 8 (see Figure V). Engagement of the contacts I closes an alternating current circuit to a rectifier 9 which feeds direct current to the magnetic relay 8. The magnetic flux set up in the relay keeps the contacts I closed, thereby shunting the alternating current around the transitory switch. The con tacts I remain closed until the contacts of a stroke switch ID are opened. The stroke switch I!) is attached to a solenoid core II which operates within a solenoid coil l2, the solenoid coil I2 being supplied with direct current from the rectifier 9. The condenser l3 and resistor l4 serve to prevent excessive arcing at the contact points of the stroke switch I0.

When the contacts of the stroke switch H] are opened, the direct current circuit is broken, the magnetic relay 8 thus being de-energized and the contacts I permitted to open. The complete cycle of operation has a duration of only a fraction of a second. When the transitory switch is closed manually, contact within the switch must be maintained momentarily only, and must break automatically and positively, regardless of the length of time that the handle of the transitory switch is held in closing position. Failure of the contacts within the transitory switch to separate properly would retard or prevent de-energization of the operating circuit and result in repetition of the cycle of operation or injury to the electrical equipment.

In the transitory switch of my invention I employ a base I5, of dielectric material, on which are mounted two standard prongs l6 and H which fit conventional electric outlet receptacles. Attached by screws l8 and I9 to extensions of the prongs within the base l5 are two contact strips 20 and 2|, of thin silver alloy, possessing suitable resiliency and so formed that a slight gap 22 normally exists between their free ends. Extending through the center of the base l5 and retained by a nut 23 is a bushing 24 to which a hollow body 25 is fastened. Assembled within the body 25 is a spring steel wire clip 26 so fashioned as to conform to the cylindrical interior of the body 25 and having loops projecting through slots provided in opposite sides of the body.

A corrugated bellows 21, made of high-grade rubber or of synthetic rubber-like composition, lies within the hollow body 25 and has a disk 28, of dielectric material, held within a fold at its inner end. The disk 28 has an integral stem 28 which'projects'througfilhe bushing 24 and engages the contact strip 2|. Surrounding the bellows 21 and lying partially between two of its annular folds is a metal collar 30, the outer edge or which engages the clip 23 and is prevented thereby from moving beyond the clip 28 toward the inner end of the hollow body 25. Located inside the bellows 21 is awasher 3| upon which presses one end of an expansive coil spring 32, the other end of which presses outwardly against a disk 33 which is held within the outer end fold oi the bellows 21. Formed integrally with the disk 33 is a cylindrical boss 34 which passes inwardly through the spring 32 and the washer 3|. A narrow passage 35 ex.. tends through the disk and cylindrical boss, the inner end of the passage being counterbored and provided with an inserted cap 35 having a minute opening 31, the proper size of which has been determined experimentally. The bellows 27, with the disks 28 and 33 held in its end folds and the collar 30 held between two) of its intermediate folds, the washer 3| being pressed by the spring 32 through the bellows wall against the collar 30, and the collar lying against the spring clip 26, are all held in place by a cap 38 which is slidably fitted over the hollow body 25 and is held in place thereon by the projecting loops formed in the clip 28 which extend through openings 38 in the cap 38. The openings 39 are elongated axially to permit limited axial movement of the cap 38. The clip 26 is sufliciently flexible so i that it may be inserted within the hollow body 25 and so that the loops 26 may be thereafter pressed inwardly to permit the skirt of the cap 38 to be slid over them, whereupon the loops 26 will spring outwardly into the openings 38.

With the transitory switch thus assembled, the

prongs l8 and I! may be inserted in an outlet receptacle provided in an operating circuit such as is diagramed in Figure V. If the cap 38 be manually pressed, the operation of the bellows extending outwardly from the collar 30 will be par-' tially collapsed and air from that portion of the bellows will be forced into and expand the portion of the bellows extending inwardly from the collar. 30, thereby moving the disk 28 and stem 28 inwardly and pressing the contact strip 2| against the contact strip 28. Engagement of the contact strips 2| and 28 closes the electrical circuit.

Immediately upon compression, the air within the bellows 2'! begins to bleed out through the orifice 31, and the resiliency oi the bellows walls, plus the pressure on the end or the stem 28 exerted by the contact strip 2|, promptly move the disk 28 and stem 28 back to their normal position, thereby again opening the gap 22 between the contact strips 2| and 28. The parts are so proportioned that the closing and opening of the cap 22 take place within a very brief interval, the length of which is the same whether the cap 38 be held down by the operator or be immediately released. When the cap 33 is released by the operator, the resiliency of the bellows walls and the expansive force of the spring 32 act to push the cap back into the position in which it is shown in Figure IV. The cap 38 thus serves as a push button or handle by means of which the switch is closed. The embodiment of my invention herein shown and described is to be regarded as illustrative only, and it is to be understood that the invention is susceptible to variation, modification and change within the spirit and scope of the subjoined claims.

Having described my invention, I claim: 1. In a device of the class described, in combination, a corrugated resilient-walled bellows, means for holding intermediate folds of said bellows against movement, means for partially collapsing the portion of said bellows on one side of said holding means, resilient means for yieldingly.

resisting collapse of said portion of said bellows, and switch contacts operable by expansion of the portion of said bellows on the other side of said holding means.

2. In a device of the class described, in combi nation, a corrugatedresilient-walled bellows, means for holding intermediate folds of said bellows against movement, means for partially collapsing the portion of said bellows on one side of said holding means, resilient means for yieldingly resisting collapse of said portion of said bellows, switch contacts operable by expansion of the portion of said bellows on the other side of said holding means, and means for bleeding air from the interior of said bellows.

LAWRENCE S. WILLIAMS. 

